Apparatus for th



Oct. 3, 1939. B. F. MIESSNER a-r 1.

APPARATUS FOR THE PRODUCTION OF MUSIC 3 Sheets-Sheet 1 Original FiledDec. 1, 1933 Oct. 3, 1 939. B. F. MIESSNER ET'AL 21,225

APPARATUS FOR THE PRDDUCTIQN -OF MUSIC 1. 1935 3 Sheets-Sheet 2 dri inalFiled Dec.

O t 1939- B. F. MIESSNER ET AL APPARATUS FOR THE PRODUCTION OF MUSICOriginal Filed Dec. 3 Sheets-Sheet 3 ReiuuedOct.3,l939 I l I v MReQZIJZS 1 UNITED STATES," PATENT OFFICE I 21.225 miim'rns Foa 'rnfiraonUc'rroN or F. Miessner, Millhurn Townshfi, Essex County, and CharlesT. Jacobs, New Providence Township, Union County, N. J., assignors togliessner Inventions, Inc., a corporation of New ersey .23 Claims. (01.zit-1.13

This invention relates to musical instruments. fled from that of theinception of'the vibrations and has special reference'to those in whichthe from which said tones are translated. output sound is translatedfrom the vibrations of In the mentioned patent electric circuits withatuned vibrator or of a plurality of tuned vibrasuitable'switchesincluded therein were employed 5 tors. in the control ofthe'mechanico-electrictransla- 5 In the U. S. Patent No. 1,915,859,issued to us tion efliciency, and it is a' particular object of the June27, 1933, there was shown and claimed an instant inventionto. provideimproved such cirinstrument wherein a mechanico-electric transcuits.Another particular objectis the provision lating system associatedwitheach vibrator, and of such circuits in convenient and compact assohadapted to translate vibrations thereof into elecelation with theconventional parts of a piano. 10

tric oscillations which were in turn translated Other and allied objectswill moreiullyappear' into' sound, was maintained normally in a givenfrom the following description and the appended condition ofoperativeness or oftranslation efllclaims.

ciency, and was caused gradually (as distin- In the descriptionreference is bad to the acguished from abruptly) to assume anotherconcompanying drawings, of which: I 15 dition or efliciency upon theinception of-vibra- .Figure 1 is a vertical cross-sectional view tion 01the associated vibrator. If for example through a portion of aninstrument of the grand the first mentioned eiiiciency was of zero valuePiano type. illustrating-811 m ime of the and the second of finitevalue, the oscillations vention, this figure showing partially diagram-'produced by the translation of vibration would L fl y th m n sr 8nd 20give rise upon their translation into sound to a a u t c t at g pp rtone simulating that of a wind or similar instru- Figure 2 s a schematicdia ram of the electriment, even though the inception of the vibrationcal circuit of the main portion of Figure 1; were abrupt. This inventioncontemplates par- Figure 3 is a view of similar nature to the mainticularly instruments wherein'tbis and similar portion of Figure t illns a modified 25 arrangements are incorporated. embodiment of theinvention;

In the mentioned patent the instrument to i ur 3a is t nal wt n al ne 7which the described arrangements were applied the line 3a of Figure 3and illustrating in detail a was a piano. Therein themechanico-electric, po of that-figure;

3o translating system associated with th strin -(or Figure 5 a schematicia r m of the elecstrings) for each different, note was caused to tricalcircuit of Figure assume the second mentioned efllciency just afterFigure 5 is a View of similar nature to the impact or the hammer withsuch string, and to portion of Figure but mustmfing I retain this secondefllciency only as long as the modified embodiment of the 1117mm; and

. 5 associated key remained depressed. Therefore Figure 6 is a schematicdifl-gl'im 0f e lec rif the conventional "lou (more aptly and hereincalcircuit of Figure 5- after term d s t i i w pedal and t con I Referencebeing particularly tolfigure ventional sostenuto" pedal, althoughavailable there will be 589}! P M P q p ate'ol' meto maintain the stringin vibration after associtame frame havmg {F portion capo P 40 atedkeyrelease, were notoperative to maintain tion lb Tear Portmn thesePortions 40- the-efliciency at the second value,-the eiiiciency 1n l'flh- Intermediate Portions returning to its first value promptly uponkey of the frame'are 9 m m release. Thus in the mentioned example anoutder to avoid comphcatlon of the figure but it Wm r Y be understoodthat allportions oi the frame are be prolonged either pedal mechanicallyand electrically integral or mutu- 45 It is an important object or theinstant inveng 9 Secured underneath the wt ame portion loos shown awrest-plank II, in tion to provide in an instrument of the piano whichmay be retained tuning pins I which type, modifications of thearrangements shown do not Contact with the Imam. In the mention? Patentwhereby sustaining frame portion to may be secured insulating bush- 50 ad sosten o p a s i be rendered fully eflecings and therein respectivelyhitch pins 4. tive to perform their usual functiom- From each tuningpin, under capo or frame por- It is a broad objec op v a generallyimtion lb, over a bridge 3| and to a respective proved instrumentwhereby there are produced hitch-pin is strung a string 5. Along the top5 output tones having inceptious of nature modirear edge of frameportion la, the bottom of capo frame portion lc may be provided Bakeliteor other insulating strips 6a, 6b and 6c respectively, in order thateach string may be completely insulated from the frame I.

All the strings may lie in the same horizontal plane; therefore thereappears in the figure the main portion of,.and the apparatus associatedwith, asingle string only. The contemplation of a plurality of strings,however, is'indicated by the additional illustration '01 a particularother. tuning pin 2' and of the front portion of a particular otherstring 5 strung to tuning pin 2'.

Each string is excitable by an individual ham mer 1, having hammer taill6, shank 8i stationary flange 19, and metallic pin 82 pivoting theshank to the flange. For operating the hammers are provided keys 8, eachhaving a horizontal rearward extension 9 pivoted as at II; a particularother key, adjacent for example to the one principally appearing in thefigure, has been designated as 8 and its pivot as ill by way ofillustration. Each key 8 is operatively connected with a respectivehammer through an individual piano action mechanism ll interposedbetween the key extension '8 and the hammer shank 8|. To the rear ofeach extension 5 is secured, as by rod 14, a back-check having woodenbody 1|, leather facing 13, and felt I2 interposed between body andfacing. The parts as described in this paragraph are conventional. Itwill therefore be understood that upon depression of any key 8 itsassociated hammer I will be propelled toward and caused to strike the.

associated string 5, immediately rebounding therefrom; and that, unlessthe key manipulation be of an extreme staccato nature, the hammer tail16 upon the rebound will be driven into contact with and willfrictionally engage the leather facing '13 of the then-raised back-checkIll, and will maintain this engagement until release of the key 8. I

, Normally resting on each string and damping the same to preventappreciable vibration thereof is provided an individual damper l3including the damping pads I21; and i211. Each damper is carried at thetop of a metallic damper rod l4 which passes through common guide raili5 and is terminally secured to a damper bushing l6. This bushing ispivoted to damper lever l1; and the lever I1 is pivoted by metallic pin68 to damper flange l8, which is secured to a common rigid portion l9 asby screw 20. The forwardend of the bottom surface 68 of each damperlever I1 is very slightly spaced above the rear upper surface ofthe-extension 9 of the associated key 8, and is therefore adapted to belifted upon and throughout depression of that key. This obviously liftsthe damper I3 fromand thus de-damps the associated string throughout theperiod of key depression. The parts described in this paragraph alsowill be recognized as entirely conventional elements of the.

grand piano.

Pedals of the conventional sustaining? and sostenuto" types areschematically illustrated as 2| and 26, respectively, pivoted as at 22and 21.

. The pedals are provided with rearwardextensions rigid base ,33.

thedamper levers ll so that upon depression of the sustaining pedal 2|all the damper levers anico-electric translating system.

,through resistance 43.

will be lifted and all the strings de-damped. The top of rod 28 isconnected to a strip 38 hinged along its edge 31 to rigid portion l8, sothat upon depression of the sostenuto pedal 26 the strip 30' will beswung about its edge 8| in a clockwisedirection as illustrated. On theback of each I damper bushing I6 is provided a small horizontal tongue32; this is normally disposed outside the sector of swing of the strip36, If, however, any key 8 be already depressed and the associateddamper bushing ll therefore be in 'a raised position when pedal 26 isdepressed, the tongue 32on that bushing will be engaged by the upwardswing of strip 38 and will be held raised, together with the associateddamper l3, after release of that key and as long as pedal 26 ismaintained depressed. It is convenient to consider the sustaining pedal2| as lifting the damper ii to a slightly lower position, and toconsider the Sostenuto pedal 26 as lifting those dampers whose tonguesit may engage to a slightly higher posiare shown constructionallysimplified or modified.

therefrom only in the interest of simple illustra' tion. 7

In general in Figure 1 (as well as in similar succeeding figures) thereare shown in section only mechanical parts common in function to theseveral strings and to the therewith associated striking and dampingsystems; and conversely all such common mechanical parts have been shownin section excepting the pedal system portions 2 I--222324-24a and26-2|--2829- 28a.

In Figure 1 there is also shown he mechis includes a conductive strip 4|of small cross-section, which may be cemented to the top of a thinBakelite or other insulating strip 42 and thereby maintained in slightspaced relationship to all of the strings. The spacing of strip 4| fromthe several strings is in general just suflicient to avoid contact ofstrip and string under a condition of maximum vibration of the latter;and these individual spacings are conveniently adjusted by slightup-and-down adjustment of the rear string extremity, as by an individualscrew 35 having an annular groove 36 engaging the associated string. Ahigh resistance 43 may connect the strip 4| to the frame I, which is inan electrical sense hereinafter frequently referred to as ground. 'Meanssupplying variable D. C. po-

tentials and hereinafter described is provided between ground and eachstring; and it will be understood that by this means the minute capacitybetween strip 4| and each string is charged The value of resistance 43is preferably made high enough to render the .charge in each suchcapacity relatively incapable of rapid variation-4. e., of oscillationvariation at a frequency as high as that -of string vibration. Thereforeoscillatory variation of any of these capacities, produced as byvibration of the associated string, in turn produces an oscillatoryvoltage component across the capacity. This component is appliedthroughthe potential supan amplifying tube 44 nating currents, to theresistance 43 and appears as an A. C. voltage thereacross.'Acrosstheterminalsofresistanceflmaybe translating system-has been shownas comprising in cascade and associated circuit, amplifier 4i,potentiometer or volume control 46,

iurther amplifier 41, and loudspeaker 48. The

circuit associated with tube 44 may comprise a condenser 48 connectedbetween the tube grid ing the input circuit of amplifier 45 and theanode current source 53. To reduce the sensitivity of portions of theapparatus to stray electrostatic fields there has been schematicallyshown electrostatic shielding 54, at frame or ground potential,surrounding the the condenser 49, the grid leak 52 and tube 44.

acoustic translating A zero efllciency.

. each The illustrated anbodiments of the invention are intimatelyconcerned with the above mentioned means for supplying variable D. C.potentials between ground and each stringor in other words forcontrolling the potential of each string with respect to ground. -Inintroduction to the embodiments themselves it is point out that uponstring vibra- ,tion' the amplitude of the A. C. voltages-cross re--sistance 43, and hence the output sound produced ;by loudspeakerdescription of these ppr p i e, o

5 (excepting as deliberately modified by volume control mean potentialit may be said that there is controlled the translation efllciency ofthe metranslation anabsence of A. C. voltage across resistance 43, andanabsence of sound from loudspeaker 4! are the results of a lack of suchpotential; while a finite such efilciency and (a string being vibrated)a finite such voltage and'sound result from the existance o'f'such meanami are each proportional to its mp1- tude. This mean potentialacross'each string-tostrip 4I capacity is identical (excepting for atime lag unnoticeable by the ear an resulting from the time constant ofstrhigto-strip capacity wth resistance 43) with the potential withrespect to ground. The control of string potential with respect toground will therefore be understood to be in more generic terms thecontrol of the translation emciency.

The variation of this potential or each string is contemplated as takingplace in particular'time relation value was ordinarily supplied; thiswas gradually changed to' a modified value ,flpon associated keydepression, or in other words upon thednltiation of 'a cyclic digitaloperation comprising key g 7 21,220 plying means, which has a lowimpedanceto alterits normal output tone or sound which strip 4!, theresistance 43,

of that string s depression and subsequent release; and was restored toits normal value thecyciic operation (1. e,, upon release of the key).according to the instant invention a potential of a normal value isagain ordinarily suppliedand isagaingradually hangedtoamodifled value bythe initiation of the cyclic digital operation; but it is notnecessarily restored to tion, but is therethrough and thereaftermaintained at'itsmodified value at willby selectively operable means,spwiflcally pedals II and II. The relative normal and modified values ofpotential may be'var'ied according to the nature of it is' desired toproduce. Attention is hereinafter called to several upon the completionof value upon completion of that operaparticular relations of thesevalues adapted to produce a. like number of particular sound natures.

In the various illustrated embodiments of this invention the means forcontrolling the potential of each string may be conveniently consideredas comprising a. common source of potentials; an

- individual reactive system'associated with each string for renderingrelatively gradual all changes of string potential, an individualnormalizing circuit connected to each reactive system from a commonpoint in thesource and closed through out substantial contact with theassociated string of the associated damper; and a modifying' circuitconnected to each reactive system from another common point in thesourceand closedthroughout depresionof theassociated key. In each figure thecommon source is shown as a battery 5i having one of its terminals-thenegative by of illustration only-connected to ground by connectionthereof to some portion of the frame I, and being shunted by apotentiometer 62 having movable contacts 63 and 64. At these twocontacts may respectively terminate the normalizing circuits for allstrings and the modifying circuits for all strings. These circuitsthennselves and the reactive systems, being shown as respectivelydiflerentin diflferent embodiments, are described separately for each ofthe Figures 1, '3

c and 5. I

The reactivesystem associated with each string it in Figure 1 is simplythe condenser 81, an individual such condenser being connected from eachstring 5 to grolmdi. e.', to frame I. The associated normalizing andmodifying circuits,

ing connected to the ungrounded side ofthis condenser, are thus in this,particular embodiment also directly connected to the string; but it isconvenient to consider the potentials supplied by these circuits assupplied to the reactive system and therefrom to the string.

In Figure 1 the normalizing circuit for each string is provided asfollows: The forward portion of the damper ll for each string, includingthe damping pad-Ila, is rendered electrically conductive by impregnationwith a colloidial graphite 1 eil'ected by a dipping and drying processor a plu rality of repeated such processes. A purely surfaceimpregnation of the solid and customarily wooden portion of the damperis suillcient; and

while it is possible to illustrate only a surface impregnation of thedamping pad itself, it is to be understood that astothisparttheimpregnation solution or emulsion. This impre natiommay be 70''is contemplated as desirably extending somewhat of such material aswell as entirely satisfactory for other material. In the figures theimpregnation of surfaces appearing in elevation has been denotedby thecovering of such surfaces with small dots, or with stippling; and theimpregnation of surfaces appearing only as edges has been denoted by theshowing of such edges as heavy instead of normal lines. Afterimpregnation the damper I! will be understood to offer to electricalpotentials between the string and the rear edge 65 of the impregnatedportion a finite resistance which is the lower the stronger be theimpregnation of the portion as established by strength of impregnatingsolutiorn duration of the impregnation process, number of times ofrepetition of the process, etc. There is contemplated no precise valueof this resistance, but it is preferably relatively low compared withthe value of the resistance element next described. This may take theformof a relatively thin strip 56 of resistive material, joining theedge 65 with the damper rod ll. It may be produced by painting on theside of the damper with a relatively weak solution of the impregnatingmaterialmentioned above or provided in any other convenient manner. Thedamper g'uide rail l5 through which all the damper rods ll pass isintended in this embodiment always 'to makeelectrical contact with thedamper rods and is formed of metal. or other electrically conductivematerial. Finally this guide rail is electrically connected to thecontact I. The normalizing circuit for each string as thusxdescribed,most obviously meets the specification that it be completed throughoutsubstantial contact with the string of the associated damper.

In Figure 1 the modifying circuit for each string is provided asfollows: The ungrounded side of each reactive system or condenser 81 iswired to a lug G1 retained under the screw II which secures theassociated damper flange iii to the rigid portion l9. Each assembly ofdamper flange I8 and damper lever I1 is rendered serially conductivefrom the surface contacting with lug 61 to the bottom surface of thelever II by impregnation, as above described, of appropriate portions ofthe assembly including that surrounding the pivot pin 68. The rearportion of each key extension 9 together with the thereto secured backcheck III are similarly impregnated to provide a conductive path fromthe surface 15 to the leather facing 13. Next a conductive path isprovided from the rear surface 11 of the hammer tail 16 to the bottomsurface 18 of the hammer flange 19. This path may intennediately includetherstrlp ill) of resistive material (conveniently produced as suggestedfor'the resistive strip 66) on the hammer shank 8i; and its terminalportions may be respectively provided by impregnating the entire hammertail T6 together with the immediately adjacent portion of the shank 8iand impregnating the hammer flange 19 together with the immediatelyadjacent portion of the thereto pivotally assembly shank 8|. Finally atleast the top portion 84 of the hammer flange rail 83-, with whichportion the surfaces II of all the flanges 19 make contact, maybe madeof metal or other electrically conductive material and connected to thepotentiometer contact 64. The impregnated portions of each modifyingcircuit as thus described are preferably sufficiently impregnated sothat the total value of resistance of each, serially considered is lowcompared to the resistance value of the strip 80 included in eachcircuit. Normally and as illustrated each therefore immaterial).

modifying circuit is open, as surfaces 69 and I! are not in contact witheach other, and as surface 11 does not contact with facing 13. Theserespective portions do contact, however, at times hereinafter described;and it is therefore convenient to consider the surfaces 6! and 15 asforming the elements of a normally open switch 85, and the surface TIand facing I! as the elements of a normally open switch It.

-For convenience in consideration thereof, the circuit of Figure 1 hasbeen condensed in Figure 2. Herein appears a string 5; the translatingsystem portions "-43; the potential source Gl-BI-GS-H; a reactive systemcomprising condenser 81; a normalizing circuit including the damping padin, schematically shown, and a resistance 6G, representing the totalseries resistance of the normalizing circuit and preferably principallymade up of theresistance strip 68; and a modifying circuit includingswitches 85 and 06 (respectively comprising surfaces 'l5" and surfaceand facing 1Il3) and the resimance 80',

representing the total series resistance of the modifying circuit withswitches closed and preferably principally made up of the resistance ofstrip 80. The portions individual to a single string have been enclosedwithin a dotted line. and portions common to all the strings appeartherewithout.

With the key associated with a given string in normal or raisedposition, the normalizing circuit associated with that string has beenseen to be closed. The associated modifying circuit, however, is thenopen by virtue of the open condition of both switches l5 and 86. Thegiven string 5 has the potential of contact 63, or its normal potential,with respect to ground. Dura downward movement of the associated key 8,however, the associated switch 85 closes; and the associated damping padlid is lifted off the string, opening the associated normalizingcirever, as is consequently the modifying circuit containing it, and thestring is therefore still without urge to change its previously existingnormal potential. But almost immediately thereafter thecult. ,Theassociated switch 85 is still open, how

the string will be positively influenced to retain its modifiedpotential.

During the first portion of the upward movement of the key 8 attendantupon key release the associated switch 86 is opened, action mechanism Iibeing conventionally arranged to move the hammer tail 16 out of contactwith the backcheck at this time. This opens the modifying circuit (thelater opening of its switch 85 being Until just before the completion ofthe upward movement of the key the contact of damper with string is ofcourse prevented and the normalizing circuit is therefore maintained inan open condition. As long as this condition exists, for whatever cause,the string the appropriate use of either pedal, which will be understoodtovhcld the damper out of contact with the string throughout and afterkey release. When the damper is again brought into contact with thestring, whether upon key release or upon the completion of a pedallingoperation, the nor-v mal potential will be again presented to thereactive system; the time required by the reactive system tochange itscharge through the resistance B6 of the normalizing circuit causing thestring to assume the. normal potential gradually rather than abruptly.

Typical, but in no sense restrictive, appropriate values of theresistance strips 80 and 66 and of condenser 81 in Figure 1 may beassigned as 3 to 4 megohms, torl megohm, and .05 to .1

microfarad, respectively: It will be understood that the two resistances80 and 66, each considered in. connection with the condenser 81, are thedeterminants of the rate of assumption by the string of the modified andnormal values of potential, respectively, when these potentials arepresented to the reactive system. The lower the valueof eitherresistance the more rapid will be the corresponding such rate, while thelower the value of the capacity the-more rapid will be both such rates.If either rate be made too rapid some extraneous noises may be producedby the loudspeaker upon the closing of either modifying or normalizingcircuit; but in general a somewhat lower value of 65 than of 80 has beenfound permissible, as well as desirable in order that the reassumptionof normal potential value by the string may take place at a rapid rate.

In Figure 1 there have been included two dotted lines A-A and BB. Infurther embodiments of the invention the apparatus illustrated in Figure1 to the left of line AA and to i the right of the line BB may beemployed without change; and therefore in Figures 3 and 5, Iillustrating these further embodiments, only the instrument portionincluded between these two lines has been shown Even in this illustratedportion much of the instruments of each of Figures 3 and 5 remainsidentical with that of Figure 1, .and the description of'these figuresassumes this identity of parts similarly shown and not speciallydescribed. With this in mind reference is directed to Figure 3. Theessential points of difference of the instrument of Fig-- ure 3 fromthat of Figure 1 are the elaboration of the reactive systems for themost positive elimination of the mentioned extraneous noises without asdefinite' -a restriction of choice of string potential change rates; andthe re-arrangement of the normalizing circuits, including thearrangement of a portion of each co-extensively with a portion. of theassociated modifying circuit. Q

Each reactive system in Figure 3 includes not only the condenserB'l'connected from string to ground, but also the resistance 88 havingone extremity-connected to the string, and a condenser 89 connected fromthe second extremity of the resistance 88 to ground. The associatednormalizing and modifying circuits are, connected as by the lead 61' tothis-second extremity from the lug 61;

The co-extensive portion of mutually associated normalizing andmodifying circuits comprises a serially conductive path, provided ingeneral as in the modifying circuits of Figure 1, I

The balance'pf each modifying circuit is provided identically as inFigure -l.

The balance of each normalizing circuit may be described as follows:Below the bottom surface 69 of each damperlever I1 is provided anindividual carbon or other contact member 8 l, this being arranged tocontact with an impregnated portion of the associated surface 69 onlywhen the associated damper Ifliis in substantial-contact with itsstring. Each contact member 9| is permanently connected to, the contact63 of the potentiometer 62. In Figure 3, and more detailedly in thecross-sectional Figure 3a, there is shown an arrangement forsupporting acontact member 9| to make the desiredcontact' without significantlyinterfering with the customarily desired positive mechanical seating ofthe associated damper on its string. Thus an individual long metallicscrew 92 is threaded through the base 33 under each damper lever I1 andthrough a common conductive member 93. Partially threaded into the upperend of each screw is an inverted cup member 94, and thevcarbon or othercontact member 9| is made in the form in the top of cup member 94. Acoil spring 95 may bias the contact member 8| to its upmos't position.This bias may be adiusted ,to the weakest dependable value by rotationof the cup member 54 with respect to the screw 92, and this adjustmentlooked as by lock nut 95.. Each entire assembly may be adjusted, justdependably to contact with the.

associated surface when the associated damper contacts with its string,from underneath the base 33 by rotation of the screw 92. The commutually associated normalizing and modifying circuits; the balance of anormalizing circuit comprising the contact member 9| normally contactingwith the surface 69 and a resistance SI .which may represent-the normalresistance from the surface69 through the contact member 9| to itssupporting means; and the balance of a modifying circuit comprising asbefore the switches and 86 and the resistance '80, representing thetotal series resistance of this balance of the modifying circuit withswitches closed.

As before with the key 8 associated with a given string -5 in a normalorraised position,

of a button of inverted T-section protruding through a suitable aperturethe normalizing circuit associated with that string is obviously closed;the associated modifying circuit open, and the string at its normalpotential. During a downward movement of the key the associated switch85 closes and the. associated surface is moved upwardly out or contactwith its contact member 9|, opening the normalizing circuit. The'associated modifying circuit is not closed, however, until the switch 86therein closes; then ,the modified potential is presented to theassociated reactive system 8988-81.' By virtue of the time-required forthe-charge in the condensers to change through quite similar to thatabove described for Figures 1-2, it being appreciated that the switchwill always open before the normalizing circuit is closed by contact ofsurface 00 with the contact member 0|.

As in the case of Figure 1, the impregnation i of various circuitportions is preferably such as to result in serial resistancevalues,'excludi 8 those of the localized resistances 00,." and 00, whichare low compared to those oi the localized resistances. Typical, butagain not restrictive, appropriate values of the circuit components forFigure 3 may be assigned as 1 to Z'megohms for the total .value of 00and 00, serially considered;

' M to l megohm for the total value of 0| and 00; 1 to 2 megohms for thevalue of 88; and

.01 to .02 microfarad for the value of each of condensers 01 and 00. Asmentioned above resistance 00 may be omitted (i. e.,,theoretically shortcircuited); It is included in Figure 3 principally so that a highresistance for III may be avoided if desired.

In both the embodiments of Figures 1 and 3 the normalizing and modifyingcircuits are largely carried by operating portions of.theinstrumentconventionally provided. In this connection it may bementioned that in these embodiments the break in each modifying circuitproduced by the switches is not required for electrical purposes, butperforms the highly useful function of permitting the removal from therest of the instrument, without complicated electrical disconnections,of the keys 0 with their extensions 0, the action mechanisms II, theham- ,mers 1, etc., which portions are. conventionally made ,in the formof a removable action unit. In the embodiment of Figure 5, however, thenormalizing and modifying circuits are not carried by operating portionsof the instrument, but

may beincorporated in a separate unit which is assembled into operativerelation with the con-- ventional instrument. It will be seen in thatfigure that the various elements shown impresnated in the earlier"figures are herein unim- Dregnated, 'and that lug 01 and conductive topportion 04 of hammer flange rail 00 have been omittedas beingunnecessary. The reactive system 00I001 of Figure 3 has been employedwith each string.

The normalizing and'modifying circuit for each string arev againprovided with a co-extensive portion, in this instance optionallyincluding the resistance 00b; 'and definitely including a flat springmember I01 connected to the reactive system, through the resistance 00?)if. employed.

The balance of each of the several normalizing circuits includesaportion of a common felt or leather strip III secured to the top of acommon conductive member or plate IOI; the

plate Ill and'strip Ill being disposed above the strings and dampers,and running in a direction transverse to that of the strings and thusappearlng'in Figure '5 in section. The strip III is impregnated with thegraphite solution or emulsion, the impregnation preferably extendinginteriorly of the'strlp as above described for the damping pad lid ofFigure 1; and against this strip normally bear the several springmembers I01. These members may be terminally secured to insulating stripI00 and this in turn to plate MI in such manner that an individualspring member I 01 is disposed over each damper I 3. The plate IOI iselectrically connected to potentiometer contact 03; and thus thenormalizing circuit for each string may be traced through a resistance00b, through a spring member I01, through the vertical transverseresistance of the portion of common impregnated strip I03 beneath thatspring, and through the plate IM to the potential source.

The balance of the modifying circuit for each string is provided bypositioning above the common impregnated strip I03, and on the oppositeside of the spring members I01 therefrom, a second common impregnatedstrip I04. This may be secured to the bottom of a common conductive barI05, which in turn may be insulatively mounted to common plate IOI inany convenient manner. The common bar I05 is electrically connected tothe potentiometer contact 04. If and when the forward extremity of aspring member I01 is raised so that the spring member contacts with theimpregnated strip I04 there is closed the associated modifying circuit,which may then be traced through a resistance 00b, through a springmember I01, through the verti- ,cal transverse resistance of the portionof comeach damper I3 is provided at its top with a hex- This is adjustedso that with headed screw I00. the associated key 0 fully. depressed thescrew I00 causes the associated spring member I01 just dependably tocontact with the bottom of strip I04; and the spacing between the banI05 and the plate MI is in general such that when the associated key isfully released the top of screw I06 is but negligibly out of contactwith the bottom of the associated spring member I01. It is contemplatedthat the sustaining pedal system will be adjusted, as by collar 24a, sothat the thereby produceable raising of the dampers I 3 will beinsufficient to cause contact of any spring member I01 with theimpregnated strip I04 though of course suflicient to lift all thedampeis from out of contact with the strings and all the spring membersI01 from out of contact with strip I03. It is further contemplated thatthe collar 20a, so that the thereby produceable raising of a damper I0above the position corresponding to full key depression will be limitedto an amount permitted by the flexing of the associated spring memberI01 and by the compression of the portion of strip I04 immediatelythereabove.

The circuit -of Figure 5, condensed as have been those ofprecedingfigures, is presented in Figure 6. Herein appears .a' reactive system00-00-01; a resistance 00!: and spring member I01 forming a co-extensiveportion formutually associated normalizing and modifying circuits; thebalance of a normalizing circuit schematically shown as a contact I00"representing the top surface 01' common strip I03, and a'resistanceIIII' representing the transverse resistance 01' the strip portionopposite aspring member I01; and

the balance of a modifying circuit schematically 1 and movable (by thedamper) to its other throw adjustment or to an intermediate adjustment.

As before, with the key 8 associated with a given string 5 in a normalor raised position, the normalizing circuit associated with that stringis closed, .the associated modifying circuit open, and the string at itsnormal potential. During a downward movement of key 8 the associatedspring member I01 is raised from out of contact with the strip I03,opening the normalizing clrcult. The modifying circuit is not closed,however, until that spring member I" contacts with strip I. This will beunderstood to occur justat the completion of key depression. In contrastto the operation in the embodiments of Figures 1 and 3, the closing ofthe modifying circuit is not as positively delayed beyond the instant ofimpact of hammer with string, but it is sufficiently lateso that theassociated string is still at least substantially at its normalpotential at the in-- stant of hammer impact. When the modifying strip103.

circuit is closed the string as before assumes the modified'potentialgradually, rather that abruptly, because of thereactive system SHE-81and the resistance |Mlflb of the modifying circuit.

Again as long as a key remains depressed, and in this embodiment also aslong as the associated damper is maintained raised by ,the sostenuto.pedal whether-or not the key be maintained depressed, the associatednormalizing circuit remains open and the associated modifying circuitclosed, and the associated string is positively influenced to retain itsmodified potential.

During the first portion of the upward motion of the key attendant uponkey release the modifying circuit is opened; but the normalizing circuitis still in an open condition, and as long as this condition exists thestring retains its modified potential. This condition may be maintainedat will by the appropriate use of the sustaining pedal 2!, which will ofcourse maintain all spring members llil "out of contact with the withthe strip Hi3, whether upon the completion of key release or of a pedaloperation, the normalizing circuit for the associated string isclosedand the string gradually rather than abruptly, assumes the normalpotential. a

Typical, but not restrictive, appropriate values of the circuitcomponents for Figure 5 may be assigned as 1 to 2 megohms for the totalvalue of Ill and lllb, serially considered; to 1 megohm for .the totalvalue of I03. and 90b; 1 to 2 megohms i'or'the valueof 8B; and .01 to.02 mi;- crofarad for the value of each of' condensers 81 and II.

asigned above for analogous components of- Figure 3; and the resistancelib, analogous to the These values are analogous to those key releaseor, lip-stroke, of theswitch formed by the'respective conductive dampingpad' I la and its string 5 in Flgure.1,. of the switch formed by therespective surface 69 and its contact member When a spring member 101contacts sl' ui' Figure 1, or of the switch formed by the respectivespring I01 and the strip I03 in Figure 5.

In each of Figures 1, 2, 3, and 5 the contact 83,

to which all the normalizing circuits are connected, has been shownadjusted to the grounded extremity of potentiometer 62; and the ,contact64, to which all the modifying circuits are connected, has been shownadjusted to the opposite extremity of the potentiometer. Thus the'normalpotential of each string with respect to ground is zero and the modifiedpotential is the maximum of the battery GI. The normal translationefliciency is therefore zero and the modifled eiliciency finite; theinstrument is therefore adjusted to produce an output tone whoseinc'eption is of gradually rising amplitude. These. relative values ofpotentials, or of efliciencies, are

exemplary only; and there, have been illustrated in Figures4 and 6 othertypical adjustments of these contacts producing other relative potentialor efliciency values.

In Figure 4 the two contacts 63 and have both been shown adjusted to theungroundedfextremity of the potentiometer 62. Under such conditions thenormal and modified potentials, or

and with the illustrated percussion excitation of the strings agenerally piano-like tone will therefore be produced.

In Figure 6 the contact 63 has been shown adjusted to the ungroundedextremity of the potentiometer 62 and the contact 64 to an intermediatepoint thereon. Thus the normal potential of each string with respect toground is the maximum of the battery. 6| and the modified potential isa. fractional part of this maximum potential. The normal translationefilclenjcy is therefore of a flnite value, and the modified efficiencyis a fractional part of such value. The output tones of the instrumentwill then be characterized'by an early gradual amplitude reductionsuperimposed on any which may be inherent in the vibrations from whichthey are translated. In this case it will be obvious that with anadjustment of the contact 6! to the grounded extremity of thepotentiometer 62 this early amplitude reduction will extend to asubstantially complete elimination of the tone at a fixed short timeafter its inception, producing anapparent extreme rate of decay.

Thus the adjustment of the contacts or of equivalent switches may serveto control the dynamic characteristics of the tones; and by virtue ofthe improvedcircuit arrangements herein disclosed. the sustaining andsostenuto pedals. 2i and 28 will have a rational action under any ofthese possible adjustments.

It will be understood that there is intende 'no limitation of theinvention by virtue of the.

specific details of the illustrated embodiments thereof, and thatthe'scope of the invention is Y intended to be expressed inthefollowingclaims.

We claim:

1. The combination with a'piano including a.

eration after key release: of a translating system, normally possessinga given efficiency, for translating the vibrations of said string intoelectric oscillations; and means for causing said translating system topossess a different efllbrations of said vibrator into sound; and meansvibrator; means normally characterized by given for causing saidtranslating system to possess adifl'erent efilciency, said lastmentioned means being responsive both to operation of said primary meansand to said continued secondary means operation.

3. The combination with a musical instrument including primary controlmeans, secondary control means, and a mechanical source of oscillations'arranged to function upon and during operation of said primary means andfor continuance of functioning during continued operation of saidsecondary means after release of said primary means of a system,normally possessing a given efficiency, for translating sound from saidsource; and means for causing said translating system to possess adifferent efficiency, said last mentioned means'being responsive both tooperation of said primary means and to said continued secondary meansoperation.

4. In combination in a musical instrument, a

efllciency for translating vibration thereof into sound; a key operableat will to produce vibration of said vibrator; means responsive to keyoperation for investing said translating means with a' modifiedemciency; and means operable at will,

and influencing jointly said vibrator and said' translating means, forcontinuing said vibration and said modified efilciency after release ofsaid key. 1 v

5. In combination in a musical instrument, a

vibrator; vibration governing means therefor;

' associated with said vibration governing means for translatingvibration thereof into sound; and a pair of means'for investing "saidtranslating means with respectively different efliciencies,-said twomeans being associated with said vibration governing means fordiscontinuous, alternate operation, and said translating means beingarranged to retain each of said efficiencies until investment thereofwith the other of said efllciencies. v

6. In combination in a musical instrument, a mechanical source ofoscillations; means for goveming the operation thereof; means fortranslating sound from said source: and apair of means for investings'aid translating means with respectively different eflciencies, saidtwo means being associated with said governing means for discontinuous,alternate operation, and said translating means being arranged to retain'each of said efficiencies until investment" thereof with the other ofsaid efficiencies.

"I. In combination in a musical instrument, a

vibratori vibration governing means. therefor; and a pair of meanslforapplying two difierent potentials to said vibrator, said two means beingcans for discontinuous, alternate operation, and said vibrator beingarranged to retain each of said two potentials thereto applied untilapplication thereto of the other of said potentials.

8. The combination with a piano including a string, means fortranslating vibrations thereofinto sound, vibration governing meanstherefor including a damper portion normally resting thereon, a keydepressible to raise said damper, and a pedal depressible to maintainsaid damper raised; of means associated with said vibration governingmeans and with said damper portion thereof for. controlling thetranslation emciency of said translating means, said controlling meansbeing responsive to both said key and said pedal.

9. In combination in a musical instrument,.vibrator; means operable atwill to initiate-vibration thereof and means operable at will toterminate such vibration; means normally characterized by an efficiencyof given value for translating such vibration into sound; means forchanging said efiiciency to a modified value upon operation of saidvibration initiating means; and means associated with said vibrationterminating means, and operative only upon operation thereof, forrestoring said efiiciency to said given value.

10. In combination in a musical instrument, a vibrator; means operableat will to initiate vib ation thereof and means operable at will toterminate such vibration; means normally characterized by an efllciencyof given value for translating suchvibration into sound; means for"changing said efilciency to a modified value upon operation of saidvibration initiating means; means associated with said vibrationterminating means, and operative only upon operation thereof, forrestoring said efficiency to said given value; and. means for renderinggradual each change of said efliciency.

11; In combination in a musical instrument, a

.vibrator and means for translating vibration thereof into sound, saidmeans being arranged to retain a value of translation efficiency onceassumed thereby until positively influenced to assume another value ofefilciency; means operable at will to initiate vibration of saidvibrator and means operable at will to suppress such vibration; meansassociated with said last mentioned'means, and operative only throughoutthe operation thereof, for positively influencing said translating meansto assume a normal value of emciency; and means operative upon operationof said vibration initiating means for positively influencing saidtranslating means to assume a modified value of efllciency.

12. In combination in a musical instrument, a vibrator and means fortranslating vibration thereof into sound, said means being arranged toretain a value of translation efllciency once assumed thereby untilpositively influenced to assume another value of 'efliciency; meansoperable i at will to initiate vibration of said vibrator and meansoperable at will to suppress such vibration;

means associated with said last mentioned means,

and operative only throughout the operation thereoLfor positivelyinfluencingsaid translating means to assume a normal value ofefliciency; means operative upon operation of said vibration initiatingmeans for positively influencing said translating means to assume amodified value of efliciency; and means for rendering gradual each We ofvalue of said efliciency.

13. The combination with a musical instrument including a vibratoradapted to retain a potential assumed thereby until the applicationthereto of a diflerent potential, and vibration-sound t lating meanstherefor having an efiiciency'responsive to the potential of saidvibrator; of a damper normally resting on said vibrator; a keydepressible to raise said damper and to excite said vibrator; and meansfor controlling the potential of said vibrator, comprising meansassociated with said damper, and operative only throughout substantialcontact thereof with said vibrator. for apply n a normal potential tosaid vibrator, and means operative while said key is depressedtor-applying a modified potential to said vibrator. 14. The combinationclaimed in claim 13, further including a reactive system interposedbetween said vibrator and both-said last-mentioned two means, iorrendering gradual each change of potential or said vibrator.

15. The combination claimed in claim 13, i'ur-' ther including a pedaldepressible to maintain said damper raised, whereby to maintain saidvibrator at said modified potential after release 01' said key. 16. Incombination in a'musical instrument,

as a vibrator; a vibration-sound translating means therefor; a dampernormally resting on said vibrator; a key depressible to excitesaldvibrator and to raise'said damper; ,a ,double-throw-swltchassociated with said damper, having a pole biased a to a first throwadjustment and adapted to be moved by raising of said damper to a secondthrow adjustment; and means respectively responsive to said two throwadjustments for establishing respectively different efilciencies oi saidtranslating eans.

17. The combin tion with a piano including a plurality of strings lyingsubstantially in a plane a plurality of dampers respectively'resting onsaid strings, a plurality or keys respectivelyadapted to raise saiddampersv and to initiate vibrations of said strings, and translatingmeans associated with each string for translating vibrations thereofinto electric oscillations; 01' electric circuits for controlling theefiiciency as or the translating means associated with .each string,said circuits including a-first common conductive means disposedsubstantially above said dampers; a second common conductive meansdisposed above, and in spaced relation to. go said first conductivemeans;- and a plurality oi spring members normally biased to contactwith said. first conductive means and 1 respectively adapted to beraised bysaid dampers out oi.

contact with said :first conductive means and is into contact with saidsecond conductive means. 18.1n a piano including a string, translatingmeans associated therewith, and an electric circuit controlling saidtranslating means: piano portions in fixed relation to the extremityoi'so said string: a lever pivoted to said fixed portions; a damperconnected to said lever for movement thereby and normally resting. onsaid string; a removable mechanism adapted to oc-- cupy a predeterminedposition relative to said, g5 and portions, and includingakeyand amember adapted upon key depression to impinge upon and move said leverandtwo electric circuit portions respectively associated with saidmeclmor said key.

'nism and with said fixed pianoportions, and respectively includingconductive means on said member and on said lever, said two circuitportions being mutually connected through said two conductive meansduring key depression when said mechanism occupies said predeterminedposition.

19. In a piano including a string. translating means associatedtherewith, and an electric circuit controlling said translating means: adamper; a conductive portion included in said damper and normallyresting on said string; means for raising said damper and conductiveportion from said string and for vibrating said string; and electriccircuit control means including a switch formed mutually'by saidconductive damper'portion and said string. I I

- 0. In a. piano including a string, translating means associatedtherewith, and an electric circuit controlling said translating means:a. damper normally resting on said string; means for raising said damperfrom said string and for vibrating said string; and electric circuitcontrol means including a resiliently supported conductive member, andfurther including conductive means connected to said damper for movementtherewith and arranged to be in contact with said member when-saiddamper rests on said string and to be out oi! contact with said memberwhen said damper is raised from said string. 4

" 21. In an electrical musical instrument ca,-

pabie of simulating the musical performance .of a piano, a key, anelectrical switch operated by said key, a sustaining pedal, meanscoacting with said switch and operated by said pedal for mechanicallypreventing the operation of saidswitch during the lip-stroke of saidkey.

- 22. In a musical instrument having for an individual note an elementthe electrical potential of which eflects a control of the intensitywith which that note will be sounded, a key;

means operated by said key in its down-stroke i'or changinfl e potentialof said element from a normal value; means operated incident to theup-stroke of said key for restoring the potential of said element tosaid normal value; a. pedal operable at will; and means, coacting withsaid restoring means and operated by said pedal, for preventing theoperation 01 said restoring means while said pedal remains operatedaiter the up- I stroke oi said key.

23. In a musical instrument having for an individual note a. condenserthe electrical charge in which eiiects acontrol or the intensity withwhich that note will be sounded. a key; means operated by said key inits down-stroke for changing thecharge in said condenser from a. normalvalue; means operated incident to the up-stroke of said key forrestoring the charge in said condenser to said normal value; a pedaloperable at will; and means, coacting with said i restoring means andoperated by said pedal, for

preventing the operation oi said restoring means a while said pedalremains operated after the upnamsum r. 'r. Jacons.

